A base station in a mobile communication system refers to a system for relaying electric waves of portable terminals in a cell. The base station is mainly located on the roof of a building to relay the electric waves of the portable terminals. Accordingly, base stations exist in units of cells and control incoming/outgoing signal transmission, traffic channel definition, and traffic channel monitoring in addition to interface functions between portable terminals and switching stations in units of cells.
In addition, thanks to many advantages, control antennas capable of performing beam tilting in a vertical or horizontal direction have been widely used as antennas employed for base stations.
Furthermore, compact base stations that can reduce frequency loads and enhance call quality have been installed as systems for covering much smaller areas than the existing mobile communication service coverage. Such base station systems are used to receive data traffic intensively generated in small-scale areas. The compact base stations may be installed in buildings or homes, thereby making it possible to resolve dead spots and provide more enhanced network and convergence services.
However, the compact base stations employed for the conventional mobile communication systems have limitations in making the overall size smaller because major components mounted in the base stations, for example, a main board, a power supply unit, an antenna, a filter, a power amplification unit, and the like are stacked one above another.
In particular, although the conventional compact base stations have stable antenna characteristics with increasing cavity spaces arranged in a filter, the cavities are arranged to be narrow in a line. Therefore, the horizontal and vertical sizes of the filter having the cavities arranged therein are made larger in order to maintain the antenna characteristics satisfying customers' demands.
Particularly, since the main board and the power amplification unit are formed on one board in the conventional compact base stations, the overall size of the main board becomes large, and a problem of heat dissipation of the power amplification unit arises.